clipping the lighting result via ciel was causing banding issues with specular maps with alpha channels. rev2. also addresses the warning:

"warning X3571: pow(f, e) will not work for negative f, use abs(f) or conditionally handle negative values if you expect them" since it was coming from the same line

Engine/source/lighting/advanced/glsl/advancedLightingFeaturesGLSL.cpp

@@ -533,7 +533,8 @@ void DeferredPixelSpecularGLSL::processPix(  Vector<ShaderComponent*> &component
    AssertFatal( lightInfoSamp, "Something hosed the deferred features! Can't find lightInfoSample" );
 
    // (a^m)^n = a^(m*n)
-   meta->addStatement( new GenOp( "   @ = pow(d_specular, ceil(@ / @)) * @;\r\n", specDecl, specPow, constSpecPow, specStrength ) );
+   meta->addStatement( new GenOp( "   @ = pow( abs(@), max((@ / AL_ConstantSpecularPower),1.0f)) * @;\r\n", 
+      specDecl, d_specular, specPow, specStrength ) );
 
    LangElement *specMul = new GenOp( "@ * @", specCol, specular );
    LangElement *final = specMul;

Engine/source/lighting/advanced/hlsl/advancedLightingFeaturesHLSL.cpp

@@ -479,7 +479,7 @@ void DeferredPixelSpecularHLSL::processPix(  Vector<ShaderComponent*> &component
       "DeferredPixelSpecularHLSL::processPix - Something hosed the deferred features!" );
 
    // (a^m)^n = a^(m*n)
-   meta->addStatement( new GenOp( "   @ = pow( @, ceil(@ / AL_ConstantSpecularPower)) * @;\r\n", 
+   meta->addStatement( new GenOp( "   @ = pow( abs(@), max((@ / AL_ConstantSpecularPower),1.0f)) * @;\r\n", 
       specDecl, d_specular, specPow, specStrength ) );
 
    LangElement *specMul = new GenOp( "float4( @.rgb, 0 ) * @", specCol, specular );